what is the periodic table? compact way of organizing elements contains a lot of information allows...

What is the periodic table?

• compact way of organizing elements• contains a lot of information • allows us to make predictions about

behavior and properties of elements based on their positions in PT

• Element Song

History of the Periodic Table

• end of 1700’s – less than 30 elements known

• many elements discovered during 1800’s

• many experiments done to determine atomic masses of the new elements

John Newlands

• 1864: if arrange elements by atomic mass – properties: repeat every 8th element

• Law of Octaves – did not work for all known elements

• Key Idea was correct: properties of elements do repeat in periodic manner

Mendeleev & Meyer1869: Mendeleev produced 1st accepted PT

– elements: in columns according to ↑ atomic mass – elements with similar properties grouped together

•predictedpredicted existence & properties of undiscovered elements

• not totally correct –more accurate atomic mass calculations showed some elements were not in right place

Remember

1860’s:

• Dalton’s billiard ball model of the atom

• NO subatomic particles yet discovered

1913 – Henry Moseley

• by 1913, protons & electrons discovered– neutrons were predicted

• Moseley determined atoms of each element contain unique # protons (= atomic number)

• re-arranged Mendeleev’s PT according to atomic number instead of atomic mass

• problems with elements in wrong place disappeared

Periodic Law

There is a periodic repetition of the elements chemical and physical properties if they are arranged by increasing atomic numberincreasing atomic number

Glenn Seaborg: 1950’s

• Lanthanide and Actinide Series

Seaborg

Mendeleev

Mosley

Newlands

Classifying the Elements

• 2/3 (75%) of elements are metalsmetals• remaining elements: non-metalsnon-metals &

metalloidsmetalloids (semi-metals)• metalloids:

– have properties of both metals & non-metals

• staircasestaircase:: – dividing line between metals & non-metals – elements to left are metals (except H)– elements to right are non-metals

Vocabulary of PT• columns called groupsgroups or familiesfamilies

– today: #1 thru 18, Arabic numerals– past: A & B groups, Roman numerals

• A-Group (tall columns)– columns 1,2,13-18 (= representative elements)– IA – 8A

• B-Group (short columns)– transition metals (columns 3-12)– IB - 8B

• rows are called seriesseries or periodsperiods– #1 thru 7

Column numbering (1 18) left to right

Period numbering (1 7) top to bottom

Names of FamiliesAKA: A group elements

Group 1 = Alkali Metals

Group 2 = Alkaline Earth Metals

Group 13 = Boron family

Group 14 = Carbon family

Group 15 = Nitrogen family

Group 16 = Oxygen family

Group 17 = Halogens

Group 18 = Noble Gases

AKA B group elements

Groups 3-12: Transition metals

Transition Metals

• Groups 3 through 12

• AKA group B elements

• Actinide & Lanthanide series – inner transition elements

• put the COLOR in your life– form brightly colored salts/solutions

Elements that are gases at STP

Diatomics:

H2, N2, O2, F2, Cl2

Monatomics: noble gases He, Ne, Ar, Kr, Xe, Rn

Two elements are liquid at room temperature

Br2 (non-metal) and Hg (metal)

All other elements are solids at room temperature

Structure of Periodic Table

• closely related to electron configuration of each element

Energy Levels = Row Number

• elements in same row have same # of principal energy levels – so # of principal energy levels = to row #

Going Across Row 2:Going Across Row 2:

2-8Ne18 (VIIIA)

2-7F17 (VIIA)

2-6O16 (VIA)

2-5N15 (VA)

2-4C14 (IVA)

2-3B13 (IIIA)

2-2Be2 (IIA)

2-1Li1 (IA)

ConfigurationElementFamily

Valence Electrons

• chemical behavior determined by # valence electrons

• elements with same # valence electrons will have similar chemical properties– elements in same column have similar

chemical properties

Going Down Column 1:Going Down Column 1:

2-8-18-32-18-8-1Fr7

2-8-18-18-8-1Cs6

2-8-18-8-1Rb5

2-8-8-1K4

2-8-1Na3

2-1Li2

1H1

ConfigurationElementPeriod

Valence Electrons

414 or IVA

313 or IIIA

22 or IIA

11 or IA

Number of Valence Electrons

Group

PROPERTIES of the

Elements

Properties of Metals

• malleable – flattened into sheets

• ductile – drawn into wires & tubes

• have Luster

• good conductors of heat & electricity

• solid at room temperature (except Hg)

• metals lose electrons & form positive ions ““Metals are losersMetals are losers””

• low ionization energy

• low electronegativity

Properties of Non-metals• generally gases or solids (except Br2)• solids are brittle• solids are dull• poor conductors of heat & electricity• non-metals gain electrons & form negative ions ““Non-metals are winnersNon-metals are winners””• high ionization energy• high electronegativity

Properties of Metalloids7 metalloids:

– 5 on right of staircase: B,Si,As,Te,At– 2 on left of staircase: Ge,Sb

Each metalloid has some metallic and some non-metallic properties

example: Sishiny like metal but

brittle like non-metal